The present invention relates to a liquid cooling system, being suitable for use within an electronic apparatus, including such as a notebook-type personal computer, for example, and further a desktop-type personal computer, a home server, a projector, and a media storage, etc., wherein cooling can be achieved, effectively, through the liquid cooling, and further relates to an electronic apparatus using the liquid cooling system therein.
A semiconductor element, which is applied within the electronic apparatus, such as, the computer or the likes mentioned above, in particular, a CPU, generating heat when it operates, as being a representative one of such the semiconductor elements. In particular, in recent years, due to demands for high speed of processing and/or high capacity, upon such the semiconductor elements, a value of heat-generation therefrom is in a tendency of increasing, more and more. Since such the semiconductor element loses the functions thereof, remarkably, when the temperature thereof exceeds a predetermined value, in general; therefore, in particular, with such the semiconductor element having a large heat-generation value, there is a necessity of providing a means for cooling, actively or aggressively. Conventionally, as a technology for cooling down the semiconductor element in such the electronic apparatus, various ones are already known and/or proposed, such as, through heat conduction, air cooling, applying a heat pipe therein, and further applying a liquid coolant or refrigerant therein.
Among of those technologies for cooling down such the semiconductor element, a one of cooling with applying the liquid cooling is most effective, in particular, for the semiconductor element having the large heat-generation, such as, the CPU mentioned above, for example, representatively. Further, a cooling method of applying such the liquid cooling therein is also already described and known in the details thereof, in the following Patent Documents 1 through 4. However, the cooling methods relating to those conventional arts are limited, in particular, only to a use in a large-scaled computer (or, so-called a mainframe).
A reason thereof lies in that the liquid cooling apparatus comes to be large in the sizes, because such the liquid cooling system relating to the conventional arts mentioned above needs a large number of parts, which are exclusive use for the liquid cooling, such as, a pump, a piping system, a radiator, etc., and further, in that it is difficult to maintain the reliability of using a liquid for cooling, comparing to other cooling method. In addition thereto, there can be also pointed out other reason that, the semiconductor element, having such a large heat-generation of a degree of necessitating the liquid cooling therein, was hardly applied therein, other than the field of the large-scaled computer, in the conventional arts.
On the other hand, differing from such the large-scaled computer as was mentioned above, a technology of applying the liquid cooling system within a small-size electronic apparatus is described and is already know in the following Patent Document 5, for example. In more details thereof, this conventional art relates to an apparatus, in which the cooling is obtained by running a liquid therein while connecting between a heat-receiving jacket attached with the semiconductor thereon and a radiator located at a position separated from it, through so-called flexible tubes.
In addition thereto, there is also know a cooling apparatus for cooling an electric equipment, such as, a thyristor or an inverter or the like, wherein a pure water having high dielectric strength is applied as the cooling water, for the purpose of preventing an accident of short-circuit from causing between the electrodes thereof, in particular, due to lowering of the dielectric strength if applying a running tap water (or, a city water) or a water for industrial use, etc., in the place thereof, into which a large amount of electrically conductive materials dissolves therein, and also where an ion-exchange resin is provided within a pure-water tank for maintaining high purity of the pure water, for example, in the following Patent Document 6.
Patent Document 1: Japanese Patent Laying-Open No. Hei 5-335454 (1993);
Patent Document 2: Japanese Patent Laying-Open No. Hei 6-97338 (1994);
Patent Document 3: Japanese Patent Laying-Open No. Hei 6-125188 (1994);
Patent Document 4: Japanese Patent Laying-Open No. Hei 10-213370 (1998);
Patent Document 5: Japanese Patent Laying-Open No. Hei 6-266474 (1994);
Patent Document 6: Japanese Patent Laying-Open No. 2003-185321 (2003).
However, as was mentioned above, the heat-generation goes up, every year, of the semiconductor element, being the heat-generation parts to be used within those electronic apparatuses, as such, the personal computer, the home server, the projector, and the media storage, etc., in particular, in recent years, and therefore, the cooling comes to be insufficient, obtained by means of such the air-cooling using the heat-conduction and/or a forced circulation air-cooling of the conventional arts, or the cooling through the heat pipe, only.
Then, an attention is paid upon the technology described in the Patent Document 5 mentioned above, and with this technology, a case of the personal computer is made of a metal material having superior heat-conductivity, so that the case itself can be utilized to be a heat-radiation plate, thereby enabling the personal computer to receive the liquid cooling system within the case thereof.
However, installing such the liquid cooling system of using the liquid coolant or refrigerant into an inside of the personal computer further causes a new problem. Namely, within the liquid cooling system to be applied into such the personal computer, an amount of the coolant or refrigerant is very small, such as, the water, typically, which can be held within an inside thereof (i.e., about 1/1,000 in the amount, comparing to that of the cooling liquid that is used within the large-scaled computer), and in addition thereto, further the working temperature thereof is relatively high. For this reason, if corrosive ion dissolves from a portion in contact with the coolant or refrigerant, even in a small amount thereof, in particular, from the parts made of organic materials (i.e., parts made of synthetic resin), then due to that corrosive ion, the liquid quality of the cooling liquid, being small in the amount thereof, is easily degraded as a whole; i.e., there is a problem that corrosion is promoted, in particular, upon the parts made of the metal materials, such as, the heat-receiving jacket and/or the radiator, etc. And further, such the problem is fatal, in particular, for the liquid cooling system to be applied within the electronic apparatus, including the personal computer therein, since it is desirable that those parts, including piping portions therein, are made of the metal materials as far as they can, for the purpose of lowering leakage of the liquid coolant or refrigerant held within the inside, through vaporization thereof, and thereby maintaining the cooling operation for a long time-period (for example, around 5–10 years as a term of guarantee). Moreover, in a case if causing the water leakage due to such the corrosion, it also causes an important problem, such as, that the functions of the electronic apparatus are stopped, or the like; therefore, it is indispensable to apply a countermeasure for the corrosion control (or, an anticorrosive means) upon the parts, which are in contact with the cooling liquid.